The R5eIII – Photos at Mt Washington Auto Road

While waiting for the winds at the summit to subside from 80mph+,  I took some shots of the latest incarnation of the R5e – now with 3kwh of LiFePO4, courtesy of Mike Corbin at Sparrow Motors.  Enjoy!

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5 responses to “The R5eIII – Photos at Mt Washington Auto Road

  1. I’m curious, I see no wire mess BMS, so did you go with Bottom or Top Balancing or are you jsut winging it?

    • For now I’m top balancing with an individual cell charger – a Turnigy – occasionally, and “bulk” charging regularly. I’m monitoring the individual cells pretty carefully, and getting a Cell Log set up within the next few days. I’ve been told that the CALB cells will work really well doing it this way, it’s basically the same way I handled the RC lipo. A little inconvenient, but it forces you to pay close attention.

      The controller has the LVC set to 50V (which would be 2.0V per cell or so, basically to avoid it cutting out if I pull enough to drop the voltage down below 60V (which is where I had it set before, and it cut out a few times when I really honked on it). I monitor the pack voltage constantly, and, for example, on the Mt Washington climb didn’t hit lower than about 62V for no more than a few seconds. The pack then settled out at around 3.29V after resting, down from 3.3V.

      Probably I’ll eventually get individual chargers for each cell. I like that solution far better than running a BMS, such as they are.

      • The problem with Top Balancing is that since all cells are filled to the max, the weakest cell will become empty before the others. And as the others still have energy left they are quite capable of killing that weak cell. You might not even see this happening because your total voltage may be still pretty good, even if a single cell is gone to zero or below. So you basically end up needing the mess of wires to monitor each cell individually.

        Compare to Bottom Balancing where you drain all cells and then only handle them as a single pack. The cells are unable to kill their buddy the weak cell since they all get empty at the same time and thus have no power left to kill anyone. Also you don’t have to, or even should not, charge cells individually, only together as one, which makes everything as simple as it gets. And I like simple. 🙂

  2. Having said that, they are your cells and you can obviously do whatever you want with them. 🙂

    • LOL! You’ve been talking to my Mother? …sounds like her, except it would have been, “I’m not going to tell you what to do, you’re gonna do what you want anyway”.

      But yeah, the debate rages on, and these are good points. I’m not particularly married to these cells, but if I like them I’m going to have to do something more formal, for sure.

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